Roof supports



May 10, 1966 D. H. CANNON ETAI. 3,250,507

ROOF SUPPORTS Filed Nov. 30. 1964 a //////////7/f/G f- &\\ 1/3 (DML 75 JF/a?.

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AT1-cna maw United States Patent Oce 3,250,507 Patented May 10, 1966 s Claims. (ci. :4s-351) This invention relates to roof supports suitable for use in a mine and including a proper member associated with a second member that engages either the roof or the oor, and that will be referred to hereinafter in the generic sense as a surface-engageable roof or tloor engaging member, the proper member being resiliently urged to a predetermined angular position, either inclined or upright, relative to the surface-engageable member.

The present invention provides a roof support including a prop member associated with such a surface-engageable member, resilient means in a compressed state acting between the proper member and the surface-engageable member to urge the prop member to a predetermined angular position relative to the surfaceengageable member, and retaining means operating independently of at least one of the said members to retain the resilient means in the compressed state. Before the prop member can move angularly relative to the surface-engageable member, a prop-displacing force must overcome force exerted by the resilient means in its compressed state. When the prop member does move angularly relative to the surface-engageable member, the prop member further Cornpresses a portion of the resilient means, and the retaining means holds the remainder of the resilient means in the compressed state. When the prop-displacing force is removed, the further compressed portion of the resilient means exerts a strong restoring force on the prop member. The predetermined angular position of the prop member, especially as shown herein may be `such that the longitudinal axis of the prop member is inclined to the perpendicular to the root or floor.

The resilient means may act upon the prop member in a direction substantially parallel to the longitudinal axis of the prop member. The prop member may have one or more laterally-extending projections upon which the resilient means acts.

The resilient means may include one or more bodies of resilient non-metallic material, for example, of elastomeric material. A series of bodies of resilient nonmetallic material may be spaced around the prop member. Alternatively, the resilient means may include one or more metallic springs.

The retaining means may be carried by the surfaceengageable member and operate independently of the prop member. The retaining means may restrict lateral movement of the prop member.

One embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings of which,

FIGURE l is a cross-sectional view of part of a mine roof support, and

FIGURE 2 is a plan view of the part of the roof support of FIGURE 1 with the prop and protective shroud removed.

With reference to the accompanying drawings, a mine roof support is illustrated as including a floor-engaging member in the form of a beam 1 with an upper part 2 and a lower part 3 which rests on the oor of a coal-mine. Alternatively a roof-engaging member may be similarly arranged, although inverted. The beam l supports a uid-pressure-operated telescopic prop 4. Only the lower portion of the prop 4 is shown in the drawing; the upper telescoping portion carries a suitable roof-engaging member. Such props are conventional except in the details shown herein, and need no further description.

The lower portion of the prop 4 includes an outer tubular member 5 which is welded to and supported by a base 6. The base 6 and part of the outer tubular member 5 are located Within the beam 1, and the outer tubular member 5 passes through an aperture of larger diameter in the upper part 2 of the beam 1. The base 6 extends externally beyond the outer tubular member S to form a [lange 7. The underside of the base 6 is convex and is mounted on a support member 8 carried by and welded to the lower part 3 of the beam 1.

An upstanding tubular element 9, carried by and welded to the support member 8,surrounds the base 6 with a small amount of clearance. The plane of the upper end of the tubular element 9, in the form selected to illustrate the principle, is inclined to the iloor at a small angle, for example 3 as shown, and supports a iirst ring 11 which surrounds but is not secured to the outer tubular member 5 and, when the prop 4 is in its predetermined angular position, also rests upon the upper surface of the Ilange 7. The predetermined angular position of the prop 4 in this embodiment, as determined by the inclined plane of element 9 whereon ring 11 rests, is one in which its longitudinal axis is inclined by 3 to the perpendicular to the tloor.

A series of separate bodies 12 of resilient non-metallic material for example an elastomer such as rubber, are supported by an-d spaced around the ring 11. The bodies 12 are retained in position by guide pegs 10 upstanding from the ring 1l. A second ring 13 surrounds the outer tubular member 5 and rests upon the rubber bodies 12. A clamp plate 14 with an aperture through which the outer tubular member 5 passes is secured by a series of bolts 15, say four in number to the upper part 2 of the beam 1 and, as shown in FIGURE l, acts upon the second ring 13 to maintain the rubber bodies 12 in a compressed state. The clamp plate 14 supports a flexible `shroud 16 which engages the outer tubular member 5 to minimize the risk of dirt entering the beam 1. This shroud completely covers the aperture in clamp plate 14 through which tubular member 5 passes.

The upstanding tubular element 9 has an extension 17 which surrounds the first ring 11 with a limited amount of clearance, or element 9 and extension 17 may be made integral, with an inclined internal shoulder corresponding to the upper edge of element 9.

Due to the inclination of the plane of the upper end of the upstanding tubular element 9 and because the rst ring 11 carrying the rubber bodies 12 rests upon the upstanding tubular element 9, some rubber bodies 12 are more compressed than others, although all are compressed in some degree. When the prop 4 is in its predetermined angular position, as shown in the drawing, the rubber bodies 12 are retained in their compressed state by the clamp plate 14 and the upstanding tubular element 9, and the rubber bodies 12 do not exert any force on the ange 7 of the prop 4.

In use of the roof support, which may include two or more props 4 supported by the oor beam 1, the roof support is so arranged that, when the prop 4 is in its predetermined angular position, the upper end of the prop 4 is inclined towards the coal face. If a force is exerted on the roof support tending to move the prop 4 angularly relative to the oor beam 1, this force must rst overcome the pre-load in the rubber bodies 12 on one side before the prop 4 will move, since the rubber bodies 12 on the other side exert no force on the tiange '7. For example, if the force is tending to tilt the prop 4 3 to the right in FIGURE 1, the force must rst overcome the compression of the rubber bodies 12 on the left before the prop 4 will move, since the rubber bodies 12 on the right are held by the opstanding tubular element 9 and exert no force on the flange 7.

Angular movement of the prop 4 to the right causes the left hand side of the flange 7 to move upwardly with the result that the left hand side of the first ring 11 also moves upwardly, leaving the upstanding tubular element 9, and the rubber bodies 12 on the left are further com pressed, The right hand side ofthe flange 7 moves downwardly, but the right hand side of the ring 11 is supported by the tubular element 9 and the rubber bodies 12 on the right hand side remain in their pre-compressed state and exert no force on the ange 7. Thus a predetermined force on the prop 4 is necessary, depending upon the amount of pre-compression of the rubber bodies 12, before the prop 4 can be moved from its predetermined angular position.

Conversely, when the prop 4 is not in its predetermined angular position and the displacing force is removed, the rubber bodies 12 which have been compressed beyond their initial compression by the flange 7 will exert a strong restoring force on the prop 4. It will be seen that the opstanding tubular element 9 acts to retain the rubber bodies 12 in a compressed state independently of the angular position of the prop 4. Also, when the rubber bodies 12 act upon the flange 7, they do so in a direction which is substantially parallel to the longitudinal axis of the prop 4. During angular movement of the prop 4, the convexly-curved base 6 rolls on the upper at surface of the support member 8, the opstanding tubular element 9 limits lateral movement of the ange 7, and the extension 17 limits lateral movement of the first ring 11.

Thus the rubber bodies 12 are retained in a compressed state by the clamp plate 14 and the upstanding tubular element 9, which act independently of the prop 4.

If desired, the rubber bodies 12 could be replaced by metallic springs. Also, if desired, the tubular member 5 and Range 7, instead of being a part of the prop 4, could be arranged to slidably receive a prop in an easily-detachable manner. In this ease, either the flange 7 could be part of a member with a convex surface engaging the support member 8, or the prop could have a convex end engaging the support member 8.

Instead of the retaining means (clamp plate 14 and tubular element 9) being carried by the Hoor-engaging Cit member and operating independently of the prop, the prop may carry retaining means in such a manner that the retaining means acts independently of the floorengaging mcmber. Alternatively, the resilient means may be retained in a compressed state by a housing which acts independently of the prop and of the floor-engaging member.

We claim as our invention:

1. A mine roof support comprising a surface-engageable member, a generally upright prop member one end whereof engages said surface-engageable member, said end being formed with means outstanding therefrom, resilient material acting between said outstanding means and the surface-engageable member to retain the prop, when unstressed, in its normal generally upright position. and a retaining device acting independently of at least one of the two members, to retain the resilient material in a compressed state.

2. A mine roof device as in claim 1, characterized in that the retaining device acts independently of the prop member.

3. A mine roof support as in claim 2, wherein the retaining device is a tubular element surrounding the outstanding means, and includes a ring surrounding but free from the prop member, and resting upon said tubular element and urged onto the same by the resilient material.

4. A mine roof support as in claim 3, wherein the edge of the retaining device whereon the ring rests denes a plane inclined to the vertical, to dispose the prop member thus inclined relative to the surface-engageable member.

S. A mine roof support as in claim 1, wherein the surface-engageable member is recessed, and the resilient material, the retaining device, and the outstanding means are received within such recess.

References Cited by the Examiner FOREIGN PATENTS 10/1952 Belgium. 8/1963 France.

OTHER REFERENCES CLAUDE A. LE ROY, Primary Examiner. 

1. A MINE ROOF SUPPORT COMPRISING A SURFACE-ENGAGEABLE MEMBER, A GENERALLY UPRIGHT PROP MEMBER ONE END WHEREOF ENGAGES SAID SURFACE-ENGAGEABLE MEMBER, SAID END BEING FORMED WITH MEANS OUTSTANDING THEREFROM, RESILIENT MATERIAL ACTING BETWEEN SAID OUTSTANDING MEANS AND THE SURFACE-ENGAGEABLE MEMBER TO RETAIN THE PROP, WHEN UNSTRESSED, IN ITS NORMAL GENERALLY UPRIGHT POSITION, AND A RETAINING DEVICE ACTING INDEPENDENTLY OF AT LEAST ONE OF THE TWO MEMBERS, TO RETAIN THE RESILIENT MATERIAL IN A COMPRESSED STATE. 